Butyric acid

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Butyric acid

Butyric acid (from Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
ß??t???? = butter), also known under the systematic name butanoic acid, is a carboxylic acid

Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
with the structural formula C

Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
H

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
₃CH₂CH₂-COOH

Carboxyl group

A carboxyl group is a set of four atoms bonded together and present in carboxylic acids, including amino acid. Usually abbreviated as either CO2H or COOH, this set of atoms constitutes a functional group....
. It is found in rancid butter

Butter

Butter is a dairy product made by churning fresh or fermentation cream or milk. It is generally used as a spread and a condiment, as well as in cooking applications such as baking, sauce making, and frying....
, parmesan cheese, vomit, and body odor

Body odor

Body odor , often abbreviated as B.O., or bromhidrosis is the odor of bacterium growing on the body. These bacteria multiply rapidly in the presence of sweat, but sweat itself is almost completely odorless....
and has an unpleasant smell

Odor

An odor or odour is a volatilized chemical compound, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction....
and acrid taste

Taste

Sorry, no overview for this topic
, with a sweetish aftertaste (similar to ether

Diethyl ether

Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic odor....
). Butyric acid can be detected by mammal

Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s with good scent detection abilities (such as dog

Dog

The dog is a domesticated subspecies of the Gray Wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties....
s) at 10 ppb

PPB

PPB can stand for:* Party political broadcast, a type of political programming in the United Kingdom* Parts-per notation, a unit of concentration...
, whereas human

Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
s can detect it in concentrations above 10 ppm.

ric acid is a fatty acid

Fatty acid

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail , which is either saturation or Unsaturated compound....
occurring in the form of esters in animal fats and plant oils.

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Chemistry

Butyric acid is a fatty acid

Fatty acid

Glyceride

Glycerides, more correctly known as acylglycerols, are esters formed from glycerol and fatty acids.Glycerol has three hydroxyl functional groups, which can be esterified with one, two, or three fatty acids to form monoglycerides, diglycerides, and triglycerides....
of butyric acid makes up 3% to 4% of butter. When butter goes rancid, butyric acid is liberated from the glyceride by hydrolysis

Hydrolysis

Hydrolysis is a chemical reaction during which one or more water are split into hydrogen and hydroxide ions which may go on to participate in further reactions....
leading to the unpleasant odor. It is an important member of the fatty acid sub-group called short chain fatty acids. Butyric acid is a weak acid

Weak acid

A weak acid is an acid that dissociates incompletely and does not release all of its hydrogens in a solution i.e it does not completely donate all of its protons....
with a pKa

PKA

PKA or pKa may be:* Protein kinase A, a cAMP activated protein kinase* pKa, the symbol for Acid dissociation constant...
of 4.82, similar to acetic acid

Acetic acid

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment , and freezes at 16.7 Celsius to a colourless crystalline solid....
which has pKa 4.76. The similar strength of these acids results from their common -CH₂COOH terminal structure. Pure butyric acid is 10.9 molar

Concentration

In chemistry, concentration is the measure of how much of a given chemical substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent....
.

The acid is an oily colorless liquid that is easily soluble in water

Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
, ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatility , flammable, colorless liquid....
, and ether

Ether

Ether is a class of organic compounds which contain an ether functional group ? an oxygen atom connected to two alkyl or aryl groups ? of general formula R?O?R....
, and can be separated from an aqueous phase by saturation with salts such as calcium chloride

Calcium chloride

Calcium chloride, CaCl2, is a common Salt . It behaves as a typical ionic halide, and is solid at room temperature. It has several common applications such as brine for refrigeration plants, ice and dust control on roads, and in concrete....
. Potassium dichromate

Potassium dichromate

Potassium dichromate, K2Cr2O7, is a common inorganic compound chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications....
and sulfuric acid

Sulfuric acid

Sulfuric acid, hydrogen2sulfuroxygen4, is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry....
oxidize it to carbon dioxide

Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
and acetic acid

Acetic acid

Potassium permanganate

Potassium permanganate is the inorganic chemical compound potassiummanganeseoxygen4, a water soluble salt consisting of equal Mole amounts of potassium and permanganate ions....
oxidizes it to carbon dioxide. The calcium salt, Ca(C₄H₇O₂)₂·H₂O, is less soluble in hot water than in cold.

Butyric acid has a structural isomer called isobutyric acid

Isobutyric acid

Isobutyric acid, also known as 2-methylpropanoic acid, is a carboxylic acid with structural formula 2-CH-carboxyl group. It is found in the free state in carobs and in the root of Arnica dulcis, and as an ethyl ester in croton oil....
(2-methylpropanoic acid).

Production

It is industrially prepared by the fermentation of sugar

Sugar

Sugar is a class of edible crystalline substances, mainly sucrose, lactose, and fructose. Human taste buds interpret its flavor as sweet. Sugar as a basic food carbohydrate primarily comes from sugar cane and from sugar beet, but also appears in fruit, honey, sorghum, sugar maple , and in many other sources....
or starch

Starch

File:Amylose2.svgFile:Amylopektin Sessel.svgStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds....
, brought about by the addition of putrefying cheese

Cheese

Cheese is a food consisting of proteins and fat from milk, usually the milk of cattle, Water Buffalo, goats, or sheep's milk. It is produced by Coagulation of the milk protein casein....
, with calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the chemical formula CalciumCarbonOxygen3. It is a common substance found as Rock in all parts of the world, and is the main component of seashells, snails, and eggshells....
added to neutralize the acids formed in the process. The butyric fermentation of starch is aided by the direct addition of Bacillus subtilis
Bacillus subtilis

Bacillus subtilis, known as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium commonly found in soil....
. Salts and esters of the acid are called butanoates.

Butyric acid or fermentation butyric acid is also found as a hexyl ester

Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
(hexyl butanoate) in the oil of Heracleum giganteum (a type of cow parsnip

Cow Parsnip

The 'Cow Parsnip' is the only member of the Hogweed genus native to North America. Its classification has caused some difficulty, with recent authoritative sources referring to it variously as Heracleum maximum or Heracleum lanatum , as H....
) and as an octyl ester (octyl butanoate) in parsnip

Parsnip

The parsnip is a root vegetable related to the carrot. Parsnips resemble carrots, but are paler than most of them and have a stronger flavor. Like carrots, parsnips are native to Eurasia and have been eaten there since ancient times....
(Pastinaca sativa); it has also been noticed in the fluors of the flesh and in perspiration.

Uses

Butyric acid is used in the preparation of various butanoate esters. Low-molecular-weight esters of butyric acid, such as methyl butanoate, have mostly pleasant aromas or tastes. As a consequence, they find use as food and perfume additives. They are also used in organic laboratory courses, to teach the Fischer

Hermann Emil Fischer

Hermann Emil Fischer was a Germany chemist and recipient of the Nobel Prize for Chemistry in 1902....
esterification reaction.

Biological functionality

Butanoate fermentation

Butanoate is produced as end-product of a fermentation process solely performed by obligate

Obligate

Obligate could be:* An adjective meaning "by necessity" and used mostly in biology, especially in the phrases:** Obligate parasite, a parasite that cannot survive without its host...
anaerobic

Anaerobic organism

An anaerobic organism is any organism that does not require oxygen for growth and may even die in its presence....
bacteria

Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
. Fermented Kombucha

Kombucha

Kombucha is the Western name for sweetened tea or tisane that has been fermentation using a macroscopic solid mass of microorganisms called a "kombucha colony"....
"tea" includes butyric acid as a result of the fermentation. This fermentation pathway was discovered by Louis Pasteur

Louis Pasteur

Louis Pasteur was a France chemist and microbiologist best known for his remarkable breakthroughs in the causes and prevention of disease. His experiments supported the germ theory of disease, also reducing mortality from puerperal fever , and he created the first vaccine for rabies....
in 1861. Examples of butanoate-producing species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring....
of bacteria:

Clostridium acetobutylicum
Clostridium acetobutylicum

'Clostridium acetobutylicum', included in the genus Clostridium, is a commercially valuable bacterium. It is sometimes called the "'Weizmann Organism'", after Chaim Weizmann, who in 1916 helped discover how C....
Clostridium butyricum
Clostridium kluyveri
Clostridium pasteurianum
Fusobacterium nucleatum
Butyrivibrio fibrisolvens
Eubacterium limosum

The pathway starts with the glycolytic

Glycolysis

Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H5O3-....
cleavage of glucose

Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
to two molecule

Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
s of pyruvate, as happens in most organisms. Pyruvate is then oxidized into acetyl coenzyme A using a unique mechanism that involves an enzyme

Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
system called pyruvate-ferredoxin oxidoreductase. Two molecules of carbon dioxide

Carbon dioxide

Hydrogen

Action	Responsible enzyme
Acetyl coenzyme A converts into acetoacetyl coenzyme A	acetyl-CoA-acetyl transferase
Acetoacetyl coenzyme A converts into ß-hydroxybutyryl CoA	ß-hydroxybutyryl-CoA dehydrogenase
ß-hydroxybutyryl CoA converts into crotonyl CoA	crotonase
Crotonyl CoA converts into butyryl CoA (CH₃CH₂CH₂C=O-CoA)	butyryl CoA dehydrogenase Butyryl CoA dehydrogenase Butyryl CoA dehydrogenase is a flavoprotein.It acts upon butyryl-coenzyme A....
A phosphate Phosphate A phosphate, an inorganic chemical, is a Salt of phosphoric acid. Inorganic phosphates are mining to obtain phosphorus for use in agriculture and industry.... group replaces CoA to form butyryl phosphate Butyryl phosphate Butyryl phosphate is an intermediate in the Fermentation of butyric acid....	phosphobutyrylase
The phosphate group joins ADP Adenosine diphosphate Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate Functional group, the pentose sugar ribose, and the nucleobase adenine.... to form ATP Adenosine triphosphate This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer.... and butyrate Butyrate File:Ethyl butyrate.pngButyrates or butanoates are esters and salts of butyric acid. Examples include:* Cellulose acetate butyrate, an aircraft dope...	butyrate kinase Butyrate kinase In enzymology, a butyrate kinase is an enzyme that catalysis the chemical reactionThus, the two substrate of this enzyme are adenosine triphosphate and butanoate, whereas its two product are adenosine diphosphate and butanoyl phosphate....

ATP is produced, as can be seen, in the last step of the fermentation. Three molecules of ATP are produced for each glucose molecule, a relatively high yield. The balanced equation for this fermentation is

C₆H₁₂O₆ ? C₄H₈O₂ + 2CO₂ + 2H₂.

Acetone and butanol fermentation

Several species form acetone

Acetone

Acetone is the organic compound with the chemical formula OC2. This colorless, mobile, flammable liquid is the simplest example of the ketones....
and butanol

Butanol

Butanol or butyl alcohol , is a primary alcohol with a 4 carbon structure and the molecular formula of Carbon4Hydrogen9Oxygen....
in an alternative pathway, which starts as butyrate fermentation. Some of these species are

Clostridium acetobutylicum
Clostridium acetobutylicum

'Clostridium acetobutylicum', included in the genus Clostridium, is a commercially valuable bacterium. It is sometimes called the "'Weizmann Organism'", after Chaim Weizmann, who in 1916 helped discover how C....
, the most prominent acetone and butanol producer, used also in industry,
Clostridium beijerinckii
Clostridium beijerinckii

Clostridium beijerinckii is a gram positive, bacterium#Morphology , motile bacterium of the genus Clostridium. It has been isolated from feces and soil....
,
Clostridium tetanomorphum,
Clostridium aurantibutyricum.

These bacteria begin with butanoate fermentation as described above, but, when the pH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
drops below 5, they switch into butanol and acetone production in order to prevent further lowering of the pH. Two molecules of butanol are formed for each molecule of acetone.

The change in the pathway occurs after acetoacetyl CoA formation. This intermediate then takes two possible pathways:

acetoacetyl CoA ? acetoacetate ? acetone, or
acetoacetyl CoA ? butyryl CoA ? butanal
Butanal

Butyraldehyde, also known as butanal, is an organic compound that is the aldehyde analog of butane as well as an isomer of butanone. It is a colorless flammable liquid with an acrid smell....
? butanol.

Butyric acid function/activity

Highly-fermentable fibers like oat bran, pectin

Pectin

Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It was first isolated and described in 1825 by Henri Braconnot....
, and guar

Guar

The guar bean or cluster bean , an annual legume, is the source of guar gum. It grows best under conditions with frequent rainfall, but tolerates arid conditions well....
are transformed by colonic bacteria

Gut flora

The gut flora are the microorganisms that normally live in the digestive tract of animals. Though widely known as the "intestinal microflora", this is technically a misnomer since the word root "flora" pertains to plants and biota refers to microbial life such as bacteria other than plants....
into short chain fatty acid

Short chain fatty acid

Short chain fatty acids are a sub-group of fatty acids with aliphatic tails of less than eight carbons. They include:* Acetic acid* Propionic acid...
s including butyrate.

Butanoate has diverse and, it seems, paradoxical effects on cellular proliferation

Cell growth

The term cell growth is used in the contexts of Cell development and cell division . When used in the context of cell division, it refers to growth of cell populations, where one cell grows and divides to produce two "daughter cells"....
, apoptosis

Apoptosis

Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Programmed Cell death involves a series of biochemical events leading to a characteristic cell Morphology and death, in more specific terms, a series of biochemical events that lead to a variety of morphological changes, including Bleb , changes...
and differentiation

Cellular differentiation

In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Differentiation occurs numerous times during the development of a multicellular organism as the organism changes from a single zygote to a complex system of Tissue and cell types....
that may be either pro-neoplastic or anti-neoplastic, depending upon factors such as the level of exposure, availability of other metabolic substrate, and the intracellular milieu. Butanoate is thought by some to be protective against colon cancer. However, not all studies support a chemopreventive effect, and the lack of agreement (particularly between in vivo

In vivo

In vivo means that which takes place inside an organism. In science, in vivo refers to experimentation done in or on the living tissue of a whole, living organism as opposed to a partial or dead one or a in vitro....
and in vitro

In vitro

In vitro refers to the technique of performing a given procedure in a controlled environment outside of a living organism. Some may argue that in vitro refers to a process that is created in a "test tube"; however, Robert Kail and John Cavanaugh on page 58 in the 4th edition of Human Development: A Life-Span View cite that in fact th...
studies) on butyrate and colon cancer has been termed the "butyrate paradox". There are many reasons for this discrepant effect, including differences between the in vitro and in vivo environments, the timing of butanoate administration, the amount administered, the source (usually dietary fiber) as a potential confounder, and an interaction with dietary fat. Together, the studies suggest that the chemopreventive benefits of butanoate depend in part on amount, time of exposure with respect to the tumorigenic process, and the type of fat in the diet. Low carbohydrate diets like the Atkins diet are known to reduce the amount of butanoate produced in the colon.

Butyric acid has been associated with the ability to inhibit the function of histone deacetylase

Histone deacetylase

Histone deacetylases are a class of enzymes that remove acetyl groups from an e-N-acetyl lysine amino acid on a histone. Its action is opposite to that of histone acetyltransferase....
enzymes, thereby favoring an acetylated state of histone

Histone

In biology, histones are the chief protein components of chromatin. They act as spools around which DNA winds, and they play a role in gene regulation....
s in the cell. Acetylated histones have a lower affinity for DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
than non-acetylated histones, due to the neutralisation of electrostatic charge interactions. In general, it is thought that transcription factors will be unable to access regions where histones are tightly associated with DNA (i.e. non-acetylated, e.g., heterochromatin). Therefore, it is thought that butyric acid enhances the transcriptional activity at promoters, which are typically silenced/downregulated due to histone deacetylase activity.

External links

This article incorporates information from the 1911 encyclopedia.

Butyric acid

Chemistry

Production

Uses

Biological functionality

Butanoate fermentation

Acetone and butanol fermentation

Butyric acid function/activity

See also

External links